Working vehicle

ABSTRACT

Provided are a pair of left and right upper frames extending in a longitudinal direction; a mount frame supporting a transmission case below the upper frames; and vertical frames connecting the upper frames and the mount frame. Rear suspension arms are supported on the vertical frames. The vertical frames are configured to have upper members connected to the upper frames and lower members connected to the mount frame. The upper and lower members are separably connected.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of JapaneseApplication No. 2011-180919, filed on Aug. 22, 2011, the disclosure ofwhich is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a working vehicle in which atransmission case is supported on a vehicle body frame, the transmissioncase speed-changing a driving force from an engine and transmitting thedriving force to left and right rear wheels. More specifically, thepresent invention relates to a configuration in which the transmissioncase is detachably supported on the vehicle body frame.

2. Description of Related Art

As a working vehicle configured as described above, Related Art 1discloses a configuration in which an engine support frame is arrangedat a rear portion of a vehicle body; a suspension frame is detachablyprovided on an L-shaped pipe, the L-shaped pipe constituting the enginesupport frame; and rear wheel differentials and the like of rear wheelsare supported on the suspension frame.

In the configuration of Related Art 1, the suspension frame isdetachably provided. Therefore, a drive system of the rear wheels isdetached together with the suspension frame.

-   [Related Art 1] Japanese Patent Laid-Open Publication No. SHO    63-20284

The suspension frame disclosed in Related Art 1 achieves suspensionfunctionality by vertical displacement integral with the rear wheeldifferentials and the like that drive the rear wheels. Thisconfiguration is effective for a vehicle having a lightweight drivesystem such as a relatively small buggy.

However, for a working vehicle having a large and heavy transmissioncase, in a configuration in which a drive system of the rear wheels,including the transmission case, is supported on a suspension frame, notonly does a movable part become large and heavy, it also leads to largesuspension unit systems such as suspension springs. Therefore, there isroom for improvement.

A configuration in which a drive system can be separated from a vehiclebody frame integrally with rear wheels not only facilitates maintenanceand repairs, but also is desired in terms of assembly, because, whenassembling a working vehicle in a mass production line, the drive systemof the rear wheels can be pre-assembled and unitized.

SUMMARY OF THE INVENTION

A purpose of the present invention is to reasonably configure a workingvehicle in which a suspension system and a drive system for rear wheelscan be easily separated from a vehicle body frame.

Means for Solving the Problems

One aspect of the present invention is a working vehicle in which atransmission case speed-changing a driving force from an engine andtransmitting the driving force to left and right rear wheels issupported on a vehicle body frame. The vehicle body frame includes apair of left and right upper frames extending in a longitudinaldirection; an underframe arranged below the upper frames; and verticalframes having upper ends connected to the left and right upper framesand lower ends connected to the underframe. The vehicle body frame isprovided with a mount frame, as the underframe, supporting thetransmission case. The mount frame is provided in a manner separatedfrom or in a manner separably connected to the underframe provided at aposition forward of the mount frame. The vertical frames that connect tothe mount frame are configured in a manner that the upper ends of thevertical frames are separably connected to the upper frames or in amanner that middle portions of the vertical frames are separable.Suspension arms are supported in a manner swingable about longitudinallyorientated swing axes with respect to portions of the vertical framesthat are fixedly provided on the mount frame. The rear wheels arerotatably supported on swinging ends of the suspension arms. Rear wheeldrive shafts are provided transmitting the driving force from thetransmission case to the rear wheels.

According to this configuration, the upper ends of the vertical framesare separated from the upper frames, or the middle portions of thevertical frames are separated, and, in a case where the front positionof the mount frame is connected to the underframe, the connectingportion is separated. Thereby, the mount frame can be separated from theupper frames and the underframe. That is, because the transmission caseis supported in a fixed state on the mount frame, the suspension armsare swingably supported on the vertical frames connected to the mountframe, and the rear wheels are supported on the suspension arms, thetransmission case and the suspension arms can be integrally detached ina form of being withdrawn downward by configuring the vertical frames tobe separable. In this configuration, as compared to a configuration inwhich the transmission case is taken out upwardly, it is not necessaryto separate the drive system that transmits the driving force from thetransmission case to the rear wheels. Therefore, not only can theoperation for the separation be simplified, time and effort can also bereduced when assembling the working vehicle. Therefore, a workingvehicle is configured that allows a suspension system and a drive systemof rear wheels to be easily separated from a vehicle body frame and thatalso allows assembly time and effort in a mass production line to bereduced.

In the present invention, a dimension of the mount frame in a vehiclebody width direction is configured to be shorter than a dimension of theleft and right upper frames in the vehicle body width direction.Accordingly, of the plurality of vertical frames, those vertical framesthat are connected to the mount frame are configured in an inclinedmanner such that upper ends of these vertical frames are increasinglydisplaced toward the outside of the vehicle body. This plurality ofvertical frames is configured such that lower members have lower endsconnected to the mount frame and upper members have upper ends connectedto the upper frames. The upper members and the lower members may beseparably connected to one another.

According to this configuration, the vertical frames are configured inan inclined manner such that the upper ends of the vertical frames areincreasingly displaced toward the outside of the vehicle body, and thevertical frames are configured such that the lower members have thelower ends connected to the mount frame and the upper members have theupper ends connected to the upper frames. Therefore, for example, it isalso possible to adopt a connection form in which an inner surfaceformed in the inclined manner on a lower member contacts an outersurface formed in the inclined manner on an upper member. In thisconnection form, when the mount frame is moved downward, separation isperformed in a manner that the inner surfaces of the lower members movedownward from the outer surfaces of the upper members. This allowsseparation and connection to be easily performed.

In the present invention, the engine is connected to a position forwardof the transmission case. A support frame is provided separablyconnected to the underframe at a position forward of the mount frame. Amount support may be provided supporting the engine with respect to thesupport frame.

According to this configuration, when separating the mount frame fromthe upper frames, by separating the support frame from the underframe,the transmission case and the engine can be integrally detached in astate in which the transmission case and the engine are connected.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed descriptionwhich follows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention,in which like reference numerals represent similar parts throughout theseveral views of the drawings, and wherein:

FIG. 1 is an entire side view of a working vehicle;

FIG. 2 is an entire plan view of the working vehicle;

FIG. 3 is a plan view illustrating a transmission system of the workingvehicle;

FIG. 4 is a perspective view of a vehicle body frame;

FIG. 5 is a perspective view illustrating a detachable unit of a rearportion of the vehicle body frame;

FIG. 6 is a side view of a drive unit;

FIG. 7 is a plan view of the drive unit;

FIG. 8 is a rear view of a traveling vehicle body;

FIG. 9 is a perspective view of a state in which a speed changeoperation structure is separated from the drive unit;

FIG. 10 is a perspective view of the drive unit and the speed changeoperation structure;

FIG. 11 is a perspective view of the speed change operation structure;

FIG. 12 is a side view of the speed change operation structure; and

FIG. 13 is a rear view illustrating a detachable frame unit in aseparated state.

DETAILED DESCRIPTION OF THE INVENTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present invention onlyand are presented in the cause of providing what is believed to be themost useful and readily understood description of the principles andconceptual aspects of the present invention. In this regard, no attemptis made to show structural details of the present invention in moredetail than is necessary for the fundamental understanding of thepresent invention, the description is taken with the drawings makingapparent to those skilled in the art how the forms of the presentinvention may be embodied in practice.

In the following, an embodiment of the present invention is explainedbased on the drawings.

(Overall Configuration)

As FIGS. 1-3 illustrate, a working vehicle is configured in which atraveling vehicle body A is provided with a pair of freely steerableleft and right front wheels 1 and a pair of left and right rear wheels2; a cabin B constituting an operating unit is provided at a frontposition of the traveling vehicle body A; a cargo bed 3 is provided at arear portion of the traveling vehicle body A; and a drive unit C isprovided at a position below the cargo bed 3.

This working vehicle is of a four-wheel drive type that has a traveldrive system transmitting a driving force from the drive unit C to thefront wheels 1 and the rear wheels 2, and is configured as a utilityvehicle used for multipurpose work such as agricultural work andtransportation work. The cargo bed 3 is configured in a manner that arear end side of the cargo bed 3 is supported in a manner swingableabout an axis P, which is in a lateral orientation with respect to arear end position of the traveling vehicle body A, and a front end sideof the cargo bed 3 can be raised via operation of a dump cylinder 4 tounload a load backward.

A hood 5 operable to open and close is provided at a front position ofthe traveling vehicle body A, and front fenders 6 covering above thefront wheels 1 are arranged at the lower left and right of the hood 5.The cabin B is provided with a windshield 8 at a front portion of acabin body 7 and doors 9 operable to open and close with respect tolateral sides of the cabin body 7.

The cabin B is provided with a driver seat 11 on which a driver sits anda laterally-long two-seater assistant seat 12 adjacent to the driverseat 11. Further, at positions in front of the driver seat 11, the cabinB is provided with a steering wheel 13 steering-controlling the frontwheels 1, a main speed change lever 14, and a parking lever 15. At lowerpositions, the cabin B is also provided with an accelerator pedal 16 asa speed change operation tool controlling a traveling speed, and a brakepedal 17 operating brake devices (not illustrated in the drawings) ofthe front wheels 1 and the rear wheels 2.

Rear fenders 18 covering above the left and right rear wheels 2 areprovided at a rear end side of the traveling vehicle body A. Brakelights 19 are provided on the rear fenders 18.

(Vehicle Body Frame)

A vehicle body frame F is provided as a strength member of the travelingvehicle body A. As FIG. 4 illustrates, the vehicle body frame F isconfigured to include a pair of left and right main frames 21 extendingin a longitudinal direction; a cabin frame unit 22 supporting the cabinB at a front position of the main frames 21; a front frame unit 23connecting front ends of the main frames 21; a pair of left and rightupper frames 24 located at positions above a rear position of the mainframes 21 and extending in the longitudinal direction of the travelingvehicle body A in a manner parallel to the main frames 21; and adetachable frame unit G supporting the drive unit C.

Square-shaped steel pipes are used for the main frames 21 and the upperframes 24, and steel products such as squared pipes and channels areused for the cabin frame unit 22 and the front frame unit 23.

The cabin frame unit 22 is configured as a structure that includes aframe body in a lateral orientation arranged at a front portion of thecabin B and a frame body in a lateral orientation arranged at a lowerside of the driver seat 11. The front frame unit 23 is a structurearranged below the hood 5, and, at each of a left and right position ofthe front frame unit 23, base end portions of a pair of upper and lowerfront suspension arms 25 configured as of a double wishbone type aresupported in a manner swingable about longitudinally orientated swingaxes. Further, lower ends of front suspension units 27 are supported bythe front suspension arms 25, the front suspension units 27 having frontsuspension springs 26 that are compressed when the front suspension arms25 swing upward. Upper ends of the front suspension units 27 aresupported by the front frame unit 23.

The left and right main frames 21 and the upper frames 24 that arearranged above the main frames 21 are connected by vertically orientedconnecting frames 28 that are formed using square-shaped steel pipes.Further, at a position adjacent to a rear end side of the main frames 21and below the upper frames 24, the detachable frame unit G is arrangedin a manner separably connected to the main frames 21 and the upperframes 24.

As FIG. 6 illustrates, the drive unit C has a configuration thatconnects an engine E, a transmission case M, and a continuously variabletransmission V (which is an example of a speed change unit). As FIGS. 5and 6 illustrate, the detachable frame unit G is configured to include amount frame 31 arranged at a lower side of the drive unit C (lower thanthe upper frames 24); two vertical frames 32 arranged on each of a leftand right side of the mount frames 31 connecting the mount frame 31 tothe left and right upper frames 24, the vertical frames 32 having aU-shaped cross-sectional shape; and a front frame 33 in a lateralorientation formed at a front end side of the mount frame 31.

The detachable frame unit G has also a functional capability ofsupporting the rear wheels 2, as described later, and is configured in amanner detachable from the vehicle body frame F, by separating thedetachable frame unit G from the other frames, in a state in which thedrive unit C and the rear wheels 2 are supported by the detachable frameunit G.

The mount frame 31 is formed by working, such as press working, a steelplate and has rib-like portions formed thereon to increase strength. Themount frame 31 has a lateral width configured to be shorter than alateral distance between the left and right upper frames 24. The mountframe 31 is provided with a pair of left and right rear mount supports34 to support the transmission case M. Further, in order to linearlyconnect two end portions of the mount frame 31 and the upper frames 24via the vertical frames 32, the left and right vertical frames 32 areprovided in an inclined manner such that an upper end side isincreasingly displaced toward the outside of the vehicle body.

That is, as FIGS. 4, 5 and 8 illustrate, as viewed in the longitudinaldirection, by providing the pair of left and right upper frames 24 at anupper portion, the mount frame 31 (which is an example of an underframeUF) at a lower portion, and the vertical frames 32 at two sides in aninclined manner such that an upper end side is increasingly displacedtoward the outside of the vehicle body, when an imaginary lineconnecting upper ends of the left and right vertical frames 32 is usedas an upper base and an imaginary line connecting lower ends of the leftand right vertical frames 32 is used as a lower base, respectivepositional relationships are configured in such a manner that aninverted trapezoid is formed of which the upper base has a longer lengththan the lower base.

The vertical frames 32 are formed using channel-shaped steel and have aconfiguration in which upper members 32A, upper ends of which areconnected to the upper frames 24, and lower members 32B, lower ends ofwhich are connected to the mount frame 31, are separably connected toone another. A portion of an upper member 32A and a portion of a lowermember 32B are overlapped, and such overlapping portions are separablyconnected to one another by inserting connecting bolts 32S through theoverlapping portions. Further, brackets 33A are provided at two endportions of the front frame 33, and, by inserting insertion bolts 33Sthrough the brackets 33A, the front frame 33 is separably connected torear ends of the main frames 21.

A support frame 35 (which is an example of the underframe UF) formedfrom a square-shaped steel pipe is arranged in a lateral orientationnear rear portions of the left and right main frames 21. Flange portions35A of left and right end portions of the support frame 35 are separablyconnected to the main frames 21 by flange bolts 35S. Further, a pair ofleft and right front mount supports 36 are formed on the support frame35 to support the engine E.

It is not necessary to use a plate material for the mount frame 31. Themount frame 31 may also be configured using a pair of left and rightsquared pipes. Further, it is also possible that the vertical frames 32are not configured to have separable middle portions. For example, it isalso possible to have a configuration in which upper end portions of thevertical frames 32 are separably connected to the upper frames 24. It isalso possible to have a configuration in which lower end portions of thevertical frames 32 are separably connected to the mount frame 31.

A lateral frame 37 in a lateral orientation, which is formed with steeland has two ends connected to the left and right upper frames 24, isprovided in a form bridging the upper frames 24 near rear ends of theupper frames 24. An upper mount support 38 is provided at a middleposition of the lateral frame 37 for supporting the transmission case Min a form where the transmission case M hangs from the upper mountsupport 38. Suspension support portions 37A are formed at two endportions of the lateral frame 37.

The above described main frames 21, mount frame 31, front frame 33, andsupport frame 35 are arranged at lower positions on the vehicle bodyframe F. Therefore, these main frames 21, mount frame 31, front frame33, and support frame 35 are collectively referred to as the underframeUF. As described above, the mount frame 31, the support frame 35, andthe lower members 32B of the vertical frames 32 are separable withrespect to other frames. Therefore, a portion of the underframe UF isconfigured to be separable.

With respect to the lower members 32B of the vertical frames 32 on eachof the left and right sides, base end portions of a pair of upper andlower rear suspension arms 39 configured as of a double wishbone typeare supported in a manner swingable about longitudinally orientatedswing axes. Further, lower ends of rear suspension units 41 aresupported by the rear suspension arms 39, the rear suspension units 41having rear suspension springs 40 that are compressed when the rearsuspension arms 39 swing upward. Upper ends of the rear suspension units41 are supported by the suspension support portions 37A of the lateralframe 37. The upper ends of the rear suspension units 41 may besupported by the upper frames 24. It is also possible that supportbrackets are provided on the upper frames 24 and the upper ends of therear suspension units 41 are supported by the support brackets.

(Drive Unit)

As FIGS. 3, 6, 7, 9, and 10 illustrate, the drive unit C is configuredwith the engine E, the transmission case M, and the continuouslyvariable transmission V integrated by connecting in this order theengine E, the transmission case M, and the continuously variabletransmission V. Two lower left and right sites of a front end positionof the engine E are supported in the pair of left and right front mountsupports 36 of the support frame 35 by lower anti-vibration mounts 45.Two lower left and right sites of a rear end position of thetransmission case M are supported in the pair of left and right rearmount supports 34 of the mount frame 31 by lower anti-vibration mounts45. An upper end portion of a hanging frame 47 that protrudes on anupper surface of the transmission case M is supported in the upper mountsupport 38 by an upper anti-vibration mount 48.

These lower anti-vibration mounts 45 and the upper anti-vibration mount48 are configured with bush-type anti-vibration rubber, and function toinhibit vibration transmitted from the drive unit C to the vehicle bodyframe F. As described above, the lateral width of the mount frame 31 isrelatively short. Therefore, the distance between the left and rightlower anti-vibration mounts 45 that support the transmission case M isdesigned to be short, and a configuration is formed in which the upperportion of the drive unit C is likely to vibrate in the lateraldirection. With regard to this point, the transmission case M issupported with respect to the lateral frame 37 in a form where the upperportion of the transmission case M is hung on the upper anti-vibrationmount 48, the lateral frame 37 being provided bridging the left andright upper frames 24. Therefore, the vibration of the drive unit C inthe lateral direction can be inhibited.

A muffler 51 having a cover 50 thereabove for protection against heat isprovided at a left side of an upper position of the transmission case Mto reduce exhaust sound of the engine E.

An internal structure of the transmission case M is not illustrated inthe drawings. However, the transmission case M has built-in a gear-typetransmission and a differential gear (not illustrated in the drawings),the transmission speed-changing a driving force speed-changed by thecontinuously variable transmission V into a plurality of speeds andperforming forward and backward switching.

As FIG. 6 illustrates, the continuously variable transmission V includesa hydraulic pump 53 of a variable capacity, axial plunger type, whichoperates by using a driving force from the engine E, and a hydraulicmotor 54 of an axial plunger type, which rotates by using hydraulic oilsupplied from the hydraulic pump 53. As FIGS. 7 and 10 illustrate, at alateral side of a rear portion of the continuously variable transmissionV, two oil filters 55 filtering the hydraulic oil are detachablyprovided. One of the two oil filters 55 is arranged on a suction side tosuck the hydraulic oil into the hydraulic pump, and the other isarranged on a drain side to drain the hydraulic oil.

In the drive unit C, a transmission system is configured in which theengine E is provided in a manner that an axis of an output shaft(crankshaft: not illustrated in the drawings) thereof is configured inthe longitudinal direction; the driving force from the engine E istransmitted to the hydraulic pump 53 of the continuously variabletransmission V by passing a transmission shaft (not illustrated in thedrawings) coupled to the output shaft through the transmission case M inthe longitudinal direction; and a driving force from the hydraulic motor54 of the continuously variable transmission V is transmitted to thetransmission case M. Further, in the transmission case M, thetransmission system is configured in a manner that the driving force isspeed-changed by the transmission, is transmitted to left and right rearoutput shafts 61 from the differential gear, and is transmitted from therear output shafts 61 via rear wheel drive shafts 62 to the left andright rear wheels 2; and in addition, as FIG. 3 illustrates, the drivingforce is transmitted from a lower output shaft (not illustrated in thedrawings) formed at a lower side and a drive shaft 63 to a front wheeldifferential gear 64, and is further transmitted from front wheel driveshafts 65 to the left and right front wheels 1.

In particular, in order to avoid contact between the drive shaft 63 andan oil pan on a lower portion of the engine E, a center position of theengine E in the lateral direction is arranged to be deviated to the leftside with respect to a center position of the transmission case M in thelateral direction. It is also possible that the center position of theengine E in the lateral direction is arranged to be deviated to theright side with respect to the center position of the transmission caseM in the lateral direction, and the drive shaft 63 is arranged on theleft side of the lower portion of the engine E.

As FIGS. 6 and 13 illustrate, the continuously variable transmission Vis configured in a manner that the hydraulic pump 53 is arranged at alower side and the hydraulic motor 54 is arranged at an upper side. Inthis configuration, an upper end level of the continuously variabletransmission V is configured to be at a position higher than an uppersurface of the transmission case M. The upper end of the continuouslyvariable transmission V protrudes above the upper surface of thetransmission case M. In order to reduce the amount of the upwardprotrusion of the continuously variable transmission V and to enlarge aconfiguration space for the muffler 51 on the left side portion of theupper portion of the continuously variable transmission V, thecontinuously variable transmission V is configured to be in an inclinedstate in a manner that the upper end side of the continuously variabletransmission V is displaced toward the right side (outside) as viewed inthe longitudinal direction. It is also possible to have a configurationin which the continuously variable transmission V is configured to be inan inclined state in a manner that the upper end side of thecontinuously variable transmission V is displaced toward the left side(outside) as viewed in the longitudinal direction, and the muffler 51 isarranged on the right side of the continuously variable transmission V.Further, it is also possible to arrange the muffler 51 on outside of thevehicle body frame F.

The continuously variable transmission V is arranged at a position suchthat a rear end portion of the continuously variable transmission Vprotrudes slightly backward from a rear end of the vehicle body frame F.As FIGS. 5 and 7 illustrate, a protector 57 protecting the rear endportion is provided at the rear end of the vehicle body frame F. Theprotector 57 is configured to include pipe frames 57A, which areseparably connected to back sides of the lower members 32B of the leftand right vertical frames 32 in the rear position, and a protectionplate 57B, which has a shape of a vertical wall and is supported by thepipe frames 57A. By separating the pipe frames 57A from the verticalframes 32, the protector 57 is separated from the vehicle body frame F,which facilitates replacement of the oil filters 55 and maintenance ofthe continuously variable transmission V.

As FIGS. 7, 9, and 10 illustrate, the engine E is provided with anintake manifold 67 on the right side of the upper surface thereofsupplying air from an air cleaner (not illustrated in the drawings). Theengine E is further provided with an exhaust manifold 68 on the leftside. An exhaust pipe 69 is arranged between the exhaust manifold 68 andthe muffler 51.

The muffler 51 is formed in a cylindrical shape, and is provided with acurved cylindrical exhaust portion 51A at a rear end to dischargeexhaust gas downward and to the left. The muffler 51 has a front endportion supported by a front bracket 58 on an upper surface of thetransmission case M and a rear end portion supported by a rear bracket59 on an upper surface of the continuously variable transmission V. Thecover 50 for protection against heat has a front end portion supportedby a screw and the like on the upper surface of the transmission case Mand a rear end portion supported by a screw and the like on the uppersurface of the continuously variable transmission V. Further, the abovedescribed exhaust portion 51A is arranged at a position where theexhaust portion 51A does not contact the cargo bed 3 when the cargo bed3 is raised, and the exhaust direction of the exhaust portion 51A isconfigured in a manner that the exhaust gas is discharged to a spacewhere no parts exist in its neighborhood. Although not illustrated inthe drawings, the front bracket 58 supporting the front end portion ofthe muffler 51 and the rear bracket 59 supporting the rear end portionof the muffler 51 are fixed with respect to screw holes formed on themuffler 51 with screws and the like. Elongated holes, through whichscrews fixing the muffler 51 to the transmission case M are inserted,are formed in different orientations on the front bracket 58 and therear bracket 59. By forming the orientations of the elongated holes thisway, dimensional errors of the muffler 51, errors of mountingpositioning, and the like are absorbed to facilitate mounting.

As described above, the upper frames 24, the mount frame 31, and theleft and right vertical frames 32 are arranged in a manner that the rearend portion of the vehicle body frame F forms an inverted trapezoid asviewed from the rear. Then, the continuously variable transmission V isarranged in an inclined manner such that the upper portion of thecontinuously variable transmission V is displaced rightward. On the leftside of the upper portion of the continuously variable transmission V,inside a corner portion on the left side of the upper portion of theinverted trapezoid, and in a vicinity of the lower side of the lateralframe 37, the muffler 51 is arranged. By doing so, the internal space ofthe vehicle body frame F can be effectively used. Further, as FIG. 7illustrates, in a plan view, the muffler 51 is arranged in a vicinity ofthe lateral frame 37 at a position overlapping the lower side of thelateral frame 37, and the muffler 51 is arranged at a positionoverlapping the upper side of the rear wheel drive shaft 62. Asdescribed above, the muffler 51 may also be arranged on the right sideinside the vehicle body frame F. Also in such an arrangement, themuffler 51 is arranged at a position overlapping the upper side of therear wheel drive shaft 62.

In particular, most of the upper surface of the muffler 51 is covered bythe cover 50, and letters such as “HOT” (not illustrated in thedrawings) are formed as projections by press working on the cover 50.Further, on the cover 50, by opening a portion of the letters and thelike formed as projections by press working, rainwater and the like areunlikely to accumulate on the upper surface; and by formingconvex-concave portions by press working, the surface area of the cover50 is enlarged and a heat radiation effect is enhanced, and at the sametime, strength is increased. The muffler 51 is fixedly connected to therear end of the exhaust pipe 69. Even after the muffler 51 is attachedto members in the vicinity of the transmission case M and the like, theexhaust pipe 69 and the muffler 51 are configured to be integrallydetachable.

(Detachment of Drive Unit)

In the configuration as described above, by separating the drive unit C,together with the detachable frame unit G and the support frame 35, fromthe vehicle body frame F, and by separating the site of the upperanti-vibration mount 48, the drive unit C can be detached in a form ofbeing withdrawn downward.

Specifically, the whole vehicle body frame F is lifted up; then, byremoving the insertion bolts 33S, the brackets 33A of the front frame 33are separated from the main frames 21; by removing the connecting bolts32S, the lower members 32B are separated from the upper members 32A,which constitute the left and right vertical frames 32 (separating thedetachable frame unit G); by removing the flange bolts 35S, the flangeportions 35A on the two ends of the support frame 35 are separated fromthe main frames 21; and by separating the site of the upperanti-vibration mount 48, the upper ends or rear ends of the rearsuspension units 41 are separated.

By performing this separation, the engine E is in a state of beingsupported on the support frame 35 by the lower anti-vibration mounts 45,and the transmission case M is in a state of being supported on themount frame 31 by the lower anti-vibration mounts 45. As FIG. 13illustrates, the drive unit C, including the engine E, the transmissioncase M, and the continuously variable transmission V, can be integrallydetached from the vehicle body frame F in a form of being moveddownward. Further, the muffler 51 is provided in the drive unit C andthe rear wheels 2 are supported on the left and right vertical frames 32via the rear suspension arms 39. Therefore, these parts can also bedetached downward together with the drive unit C.

In particular, the engine E, the transmission case M, and thecontinuously variable transmission V are heavy, and these members aredetached from the vehicle body frame F in a form of being moveddownward. Therefore, as compared to a case where these members aredetached in a form of being lifted upward, detachment can also beperformed in a form of using a hydraulic jack to lower these membersdown, for example, without the need for lifting equipment. Further, inthis working vehicle, it is also possible to adopt a configuration inwhich the front frame 33 is not connected to the main frames 21. Byadopting such a configuration, time and effort can be reduced whenseparating the mount frame 31.

(Speed Change Operation Structure)

As FIGS. 6, 7 and 9-11 illustrate, the engine E and a lower position ofthe transmission case M are connected, and a gap H is formed at an upperposition between the two members. A coupling member 71 is arranged at aposition straddling over the top of the gap H, crossing over an uppersurface of a rear portion of the engine E and projecting portions Maprotruding upward at a front portion of the transmission case M. A frontend of the coupling member 71 is bolt-connected to the engine E, and arear end of the coupling member 71 is bolt-connected to the projectingportions Ma of the transmission case M. This connection enhances thecoupling strength between the engine E and the transmission case M.

At an upper position of the coupling member 71, a tubular body 72 isprovided coaxial with a middle axis X in a lateral orientation. A middleactuation shaft 73 is rotatably supported with respect to the tubularbody 72 in a manner fitted therein. A middle position of a plate-shapedinput arm 74 connects to an end portion on a right side of the middleactuation shaft 73. A bell-crank-shaped output arm 75 connects to an endportion on a left side of the middle actuation shaft 73. A neutral cam76 connects to a middle portion of the middle actuation shaft 73.

An arm-shaped stay 77 is fixedly provided on the outside of the tubularbody 72. An end portion of an outer wire 78A of an operation wire 78 issupported by the stay 77, the operation wire 78 as a first operationdevice being linked to the accelerator pedal 16 as a speed changeoperation tool. Further, an end portion of an inner wire 78B of theoperation wire 78 connects to one end portion of the input arm 74. Aspeed control rod 79 connects to the other end portion of the input arm74, the speed control rod 79 as a third operation device transmitting anactuating force of the input arm 74 to a throttle mechanism Et of theengine E.

A speed change operation part 80 is arranged on a left side surface ofthe continuously variable transmission V. A speed change operation arm81A is provided for swinging a speed change operation shaft 81 thatprotrudes from the speed change operation part 80 in a horizontalorientation. The speed change operation arm 81A in a neutral orientationillustrated in FIG. 6 shuts off hydraulic oil supplied from thehydraulic pump 53 to the hydraulic motor 54 to stop traveling. Byswinging the speed change operation arm 81A, the hydraulic oil suppliedfrom the hydraulic pump 53 to the hydraulic motor 54 is increased and anincrease in traveling speed is realized.

One end portion of an operation rod 82 connects to the speed changeoperation arm 81A, and the other end portion of the operation rod 82connects to one arm of the output arm 75. An oil damper 83 forinhibiting rapid actuation of the speed change operation arm 81Aconnects to the other end portion of the output arm 75. As FIG. 12illustrates, a concave cam surface 76A is formed on an outer peripheryof the neutral cam 76. A neutral return arm 86 is supported on a supportpart 85 of a projecting end of an arm body 84 fixedly provided on thetubular body 72, in a manner swingable about an axis parallel to themiddle axis X. An abutment member 87 formed from an idling rollerengageable with the cam surface 76A of the neutral cam 76 is supportedon the neutral return arm 86. A biasing force of a neutral return spring88 acts on a swinging end of the neutral return arm 86.

According to this speed change operation structure, when the acceleratorpedal 16 is depressed, the inner wire 78B is pulled, and the input arm74 and the middle actuation shaft 73 rotate about the middle axis X.Along with the rotation of the input arm 74, the speed control rod 79 ispulled, and, with this operation force, the throttle mechanism Et isoperated in an acceleration direction and an engine rotation speed isincreased. Further, the output arm 75 rotates integrally with therotation of the middle actuation shaft 73 caused by the depressionoperation of the accelerator pedal 16. By a pushing operation of theoperation rod 82 linked to this rotation, the speed change operation arm81A is operated in an acceleration direction and the continuouslyvariable transmission V performs acceleration. That is, in conjunctionwith the depression operation of the accelerator pedal 16, travelingspeed can be increased by increasing the driving speed of thecontinuously variable transmission V, while inhibiting engine stall byincreasing the engine rotation speed.

Further, when the depression operation of the accelerator pedal 16 isreleased, the tension acting on the inner wire 78B from the acceleratorpedal 16 is largely reduced. Due to the biasing force of the neutralreturn spring 88 that acts on the neutral return arm 86, the abutmentmember 87 presses against and enters into the cam surface 76A of theneutral cam 76. Thereby, the middle actuation shaft 73 returns to aneutral position and the speed change operation arm 81A returns to thestop position; in addition, the throttle mechanism Et also returns to adeceleration position, and the traveling vehicle body A stops.

Specifically, in this speed change operation structure, the operationwire 78 as the first operation device transmitting the depressionoperation force of the accelerator pedal 16 is arranged on the rightside of the vehicle body. The operation rod 82 as the second operationdevice transmitting the operation force of the operation wire 78 to thespeed change operation part 80 on the left side of the continuouslyvariable transmission V is arranged on the left side of the vehiclebody. The speed control rod 79 as the third operation devicetransmitting the speed change operation force of the operation wire 78to the throttle mechanism Et on the right side of the engine E isarranged on the right side of the vehicle body. From this arrangement,using a configuration in which the middle actuation shaft 73 rotatesabout the middle axis X, the speed change operation is performed byeffectively utilizing the spaces on the two sides of the drive unit C.In this speed change operation structure, it is also possible that theoperation wire 78 as the first operation device, and the like, arearranged on the left side of the vehicle body, and the operation rod 82as the second operation device, and the like, are arranged on the rightside of the vehicle body. Further, an operation system operating thethrottle mechanism Et may be arranged on either the left or right sideof the vehicle body.

Operation Effect of the Embodiment

In this working vehicle, the drive unit C is configured by integrallyconnecting the engine E, the transmission case M, and the continuouslyvariable transmission V, and the engine E and the transmission case Mare supported by the left and right lower anti-vibration mounts 45 onthe underframe UF. Therefore, it becomes possible for the weight of thedrive unit C to be received by the lower anti-vibration mounts 45.Further, the upper portion of the transmission case M is supported bythe upper anti-vibration mount 48 on the middle portion of the lateralframe 37, the two ends of which are supported by the upper frames 24.Therefore, even when the distance in the lateral width direction betweenthe left and right lower anti-vibration mounts 45 is short, it ispossible to inhibit vibration of the upper portion of the drive unit C,thereby realizing support with superior anti-vibration capability.

By arranging the continuously variable transmission V in an inclinedmanner such that the upper portion of the continuously variabletransmission V is displaced toward one side in the lateral direction ofthe traveling vehicle body A, the space on the other side of thecontinuously variable transmission V in the lateral direction of thevehicle body is enlarged. Therefore, even when the space in which thecontinuously variable transmission V is arranged is relatively narrow,the muffler 51 can be arranged inside this space. Further, the engine Eis arranged at a front position of the transmission case M in a mannerdeviated to one side (left side) with respect to the transmission caseM; the exhaust manifold 68 is formed on one side (left side) on an upperportion of the engine E; and the muffler 51 is arranged in the samedirection as the deviation of the engine E. Therefore, the exhaust pipe69 can be linearly formed to linearly supply engine exhaust gas to themuffler 51, which simplifies the configuration of the exhaust system.

Further, as viewed in the longitudinal direction, a space of an invertedtrapezoid shape is formed inside the vehicle body frame F, the invertedtrapezoid shape being formed from the pair of left and right upperframes 24, the left and right vertical frames 32 in inclinedorientations, and the underframe UF. Inside this space of the invertedtrapezoid shape in the vehicle body frame F, the muffler 51 is arrangedat a position in the vicinity of an upper left or right corner. Thus,the muffler 51 can be arranged at a corner of the vehicle body frame Fin a state of being protected by the vehicle body frame F.

As described above, as viewed in the longitudinal direction, the vehiclebody frame F is formed in a shape of an inverted trapezoid. Bysupporting the upper ends of the rear suspension units 41 on the lateralframe 37 that connects the left and right upper frames 24, it ispossible for the orientations of the rear suspension units 41 to beclose to orientations parallel to the swing directions of the rearsuspension arms 39 (orientations perpendicular to arm surfaces of therear suspension arms 39), so that low-impact compression of the rearsuspension arms 39 can be performed.

The drive unit C and a support system of the rear wheels 2 are supportedby the detachable frame unit G. Therefore, by separating the detachableframe unit G from the vehicle body frame F, the engine E, thetransmission case M, the continuously variable transmission V, themuffler 51, and the rear wheels 2 can be integrally detached from thevehicle body frame F in a form of being withdrawn downward, and, forexample, as compared to a configuration in which the drive unit C iswithdrawn upward, the maintenance of the drive unit C becomes easy.

That is, the transmission case M is supported on the mount frame 31 bythe lower anti-vibration mounts 45; the rear suspension arms 39 areswingably supported on the vertical frames 32 connected to the mountframe 31; and the rear wheels 2 are supported on the rear suspensionarms 39. Further, the engine E is supported on the support frame 35 bythe lower anti-vibration mounts 45. From this configuration, byseparating the vertical frames 32 and separating the support frame 35from the main frames 21, the engine E, the transmission case M, thecontinuously variable transmission V, the rear suspension arms 39, andthe muffler 51 can be integrally detached in a form of being withdrawndownward, without the need of separating the drive system that transmitsthe driving force from the transmission case M to the rear wheels 2, andthus the operation for the separation is simplified.

The engine E and the transmission case M are connected at lower portionsthereof. The upper portion of the engine E and the upper portion of thetransmission case M are connected by the coupling member 71, which isarranged at a position straddling over the gap H formed by the upperportions, to enhance the coupling strength. Further, the middleactuation shaft 73 is rotatably supported by the tubular body 72, whichis provided in a lateral orientation with respect to the coupling member71. The operation force of the accelerator pedal 16 is transmitted toone side (right side) of the middle actuation shaft 73 to rotate themiddle actuation shaft 73. From the other side (left side) of the middleactuation shaft 73, the speed change operation arm 81A of thecontinuously variable transmission V is operated to perform speedchange. In such a configuration, without causing mechanical backlash andplay at the middle actuation shaft 73, a speed change operation force istransmitted with high precision from one side of the drive unit C to thecontinuously variable transmission V on the other side to realize speedchange operation.

In particular, when performing the speed change operation, bysimultaneously operating the continuously variable transmission V andthe throttle mechanism Et of the engine E, acceleration is realizedwithout causing an engine stall. When the operation of the acceleratorpedal 16 is released, the abutment member 87 formed from the idlingroller engages the cam surface 76A of the neutral cam 76. Thereby, themiddle actuation shaft 73 is rotated toward a neutral direction, and thecontinuously variable transmission V returns to the neutral position. Atthe same time, by operating the throttle mechanism Et to thedeceleration position, a stop to traveling is realized.

Other Embodiments

In addition to the above-described embodiment, the present invention mayalso be configured as follows.

(a) The underframe UF is configured without providing the front frame 33that connects to the front end of the mount frame 31. Or, in aconfiguration in which the front frame 33 is provided, the brackets 33Afor connecting the front frame 33 to the main frames 21 are notprovided. By such a configuration, when detaching the mount frame 31from the vehicle body frame F, the number of places where separation isperformed is reduced, which facilitates the operation.

(b) The rear end position of the main frames 21 that constitute theunderframe UF is configured to be the position of the support frame 35.This reduces the weight of the vehicle body frame F, and in addition,similar to the embodiment (a), when detaching the mount frame 31 fromthe vehicle body frame F, this allows the number of places whereseparation is performed to be reduced, which facilitates the operation.

(c) The support frame 35 is fixedly provided with respect to the mainframes 21. In this configuration, an operation to separate the engine Efrom the front mount supports 36 of the support frame 35 is necessary.However, a configuration for separating the support frame 35 from themain frames 21 is not necessary, which simplifies the configuration ofthe vehicle body frame F and facilitates manufacturing.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a working vehicle having atransmission system transmitting a driving force of a transmission caseprovided on a vehicle body frame to rear wheels.

It is noted that the foregoing examples have been provided merely forthe purpose of explanation and are in no way to be construed as limitingof the present invention. While the present invention has been describedwith reference to exemplary embodiments, it is understood that the wordswhich have been used herein are words of description and illustration,rather than words of limitation. Changes may be made, within the purviewof the appended claims, as presently stated and as amended, withoutdeparting from the scope and spirit of the present invention in itsaspects. Although the present invention has been described herein withreference to particular structures, materials and embodiments, thepresent invention is not intended to be limited to the particularsdisclosed herein; rather, the present invention extends to allfunctionally equivalent structures, methods and uses, such as are withinthe scope of the appended claims.

The present invention is not limited to the above described embodiments,and various variations and modifications may be possible withoutdeparting from the scope of the present invention.

What is claimed is:
 1. A working vehicle, wherein a transmission casespeed-changing a driving force from an engine and transmitting thedriving force to left and right rear wheels is supported on a vehiclebody frame, the vehicle body frame comprising: a pair of left and rightupper frames extending in a longitudinal direction; an underframearranged below the upper frames; and a plurality of vertical frameshaving upper ends connected to the left and right upper frames and lowerends connected to the underframe, the vehicle body frame being providedwith a mount frame, as a portion of the underframe, supporting thetransmission case, the mount frame being separated from or separablyconnected to a portion of the underframe provided at a position forwardof the mount frame, the vertical frames that connect to the mount framebeing configured so that the upper ends of the vertical frames areseparably connected to the upper frames or so that middle portions ofthe vertical frames are separable, suspension arms being supported to beswingable about longitudinally orientated swing axes with respect toportions of the vertical frames that are fixedly provided on the mountframe, the rear wheels being rotatably supported on swinging ends of thesuspension arms, and rear wheel drive shafts being provided transmittingthe driving force from the transmission case to the rear wheels, whereinthe engine and the transmission are structured and arranged to beremovable from the vehicle along with the mount frame while remainingconnected to each other.
 2. The working vehicle according to claim 1,wherein a dimension of the mount frame in a vehicle body width directionis configured to be shorter than a dimension of the upper frames in thevehicle body width direction, of the plurality of vertical frames, thevertical frames that are connected to the mount frame are configured inan inclined manner such that upper ends of these vertical frames areincreasingly displaced toward the outside of the vehicle body, theplurality of vertical frames that are connected to the mount frame beingconfigured such that lower members have lower ends connected to themount frame and upper members have the upper ends connected to the upperframes, and the upper members and the lower members are separablyconnected to one another.
 3. The working vehicle according to claim 2,wherein the lower members and the upper members comprise respectivecorresponding U-shaped cross-sections structured and arranged forengagement with each other.
 4. The working vehicle according to claim 3,wherein the lower members and upper members are engaged such that innerside surfaces of the lower members on an inner side of the vehicle in aleft-right direction of the vehicle and outer side surfaces of the uppermembers on an outer side of the vehicle in the left-right direction ofthe vehicle are aligned to each other.
 5. The working vehicle accordingto claim 1, wherein the engine is connected to a front position of thetransmission case, the vehicle body frame further comprises: a supportframe is separably connected to the portion of the underframe at aposition forward of the mount frame, and a mount support structured andarranged on the support frame to support supports the engine, andwherein the support frame is attached to the engine, and wherein thesupport frame, the engine, the transmission case and the mount frame areintegrally removably fixed to the vehicle.
 6. The working vehicleaccording to claim 5, wherein the mount frame and the support frame arenot directly connected.
 7. The working vehicle according to claim 1,wherein the mount frame is removably fixed to the vehicle in a rigidmanner.
 8. A working vehicle having a cargo bed, wherein a transmissioncase speed-changing a driving force from an engine and transmitting thedriving force to left and right rear wheels is supported on a vehiclebody frame, the vehicle body frame comprising: a pair of left and rightupper frames extending in a longitudinal direction; an underframearranged below the upper frames; and a plurality of vertical frameshaving upper ends connected to the left and right upper frames and lowerends connected to the underframe, the vehicle body frame being providedwith a mount frame, as a portion of the underframe, supporting thetransmission case, the mount frame being separated from or separablyconnected to a portion of the underframe provided at a position forwardof the mount frame, the vertical frames that connect to the mount framebeing configured so that the upper ends of the vertical frames areseparably connected to the upper frames or so that middle portions ofthe vertical frames are separable, suspension arms being supported to beswingable about longitudinally orientated swing axes with respect toportions of the vertical frames that are fixedly provided on the mountframe, the rear wheels being rotatably supported on swinging ends of thesuspension arms, and rear wheel drive shafts being provided transmittingthe driving force from the transmission case to the rear wheels, whereinthe cargo bed is mounted on a rear end of the upper frames, and whereinthe engine and the transmission are structured and arranged to beremovable from the vehicle along with the mount frame while remainingconnected to each other.
 9. The working vehicle according to claim 8,wherein a dimension of the mount frame in a vehicle body width directionis configured to be shorter than a dimension of the upper frames in thevehicle body width direction, of the plurality of vertical frames, thevertical frames that are connected to the mount frame are configured inan inclined manner such that upper ends of these vertical frames areincreasingly displaced toward the outside of the vehicle body, theplurality of vertical frames that are connected to the mount frame beingconfigured such that lower members have lower ends connected to themount frame and upper members have the upper ends connected to the upperframes, and the upper members and the lower members are separablyconnected to one another.
 10. The working vehicle according to claim 9,wherein the lower members and the upper members comprise respectivecorresponding U-shaped cross-sections structured and arranged forengagement with each other.
 11. The working vehicle according to claim10, wherein the lower members and upper members are engaged such thatinner side surfaces of the lower members on an inner side of the vehiclein a left-right direction of the vehicle and outer side surfaces of theupper members on an outer side of the vehicle in the left-rightdirection of the vehicle are aligned to each other.
 12. The workingvehicle according to claim 8, wherein the engine is connected to a frontposition of the transmission case, the vehicle body frame furthercomprises: a support frame separably connected to the portion of theunderframe at a position forward of the mount frame, and a mount supportstructured and arranged on the support frame to support the engine, andwherein the support frame is attached to the engine, and wherein thesupport frame, the engine, the transmission case and the mount frame areintegrally removably fixed to the vehicle.
 13. The working vehicleaccording to claim 12, wherein the mount frame and the support frame arenot directly connected.
 14. The working vehicle according to claim 8,wherein the mount frame is removably fixed to the vehicle in a rigidmanner.